Six steps of an ACL reconstruction
While the injury is still a serious one and the rehabilitation can take more than half a year, the actual procedure to reconstruct the anterior cruciate ligament in the knee is relatively simple. It typically takes less than an hour when performed by an experienced orthopedic surgeon.
Dr. Craig Levitz, who studied as a fellow under James Andrews in the 1990s and whose orthopedic practice in Lynbrook is one of the busiest in New York State, offered a step-by-step look at the surgery as it is most often done: using a sliver of the patella tendon to replace the torn ligament. Here, in essence, are the ABCs of an ACL reconstruction.
STEP ONE: ANESTHESIA
Levitz said most surgeons these days will use regional anesthesia rather than general. A block to the femoral nerve and a block to the sciatic nerve with some sedation gives the surgeon enough of a window to perform the procedure and gives the patient about 24 hours of pain relief. The patient is also given antibiotics to prevent infection.
STEP TWO: THE HARVEST
A small incision about two to three inches long is made on the front of the knee and a bone block from each end of the patella tendon is harvested. The tendon is under just two layers of skin and away from the infrastructure of the knee, so the risk of developing scar tissue in the actual joint is averted. The standard used to be to take a 25-millimeter bone plug from the patella in order to fix the new tendon in place, but that would lead to increased risk of fractured knee caps. Such an injury curtailed the comeback of Hall of Fame wide receiver Jerry Rice in 1997. These days the fixation methods and devices have improved so that a small 10-millimeter bone plug can be used. "You're really just nubbing off the tip of the knee cap," Levitz said. "That tip of the knee cap doesn't even really function." The surgeon uses an oscillating saw to remove the bone blocks and it takes about 10 minutes to complete.
STEP THREE: THE CLEANUP
The rest of the procedure is generally done arthroscopically. The camera is inserted into the knee and the old ACL needs to be cleaned out. The surgeon removes the remains of the ACL by debrideing it, essentially scraping it off the two bones it used to hold together. A little piece of it is left behind as a marker on each bone so later on the surgeon will know where to drill the hole to attach the new ligament.
STEP FOUR: THE NOTCH
The most important part of a reconstruction is the placement of the new ACL. To give themselves a more direct sight line to the location of the target area, and also to help prevent re-tearing, a notchplasty is performed. With an arthroscopic burr, the surgeon will "smooth down layer by layer" the V-shaped notch in the back of the femur. This yields a U-shaped area which lacks the sharp edges that can sometimes lead to a re-injury. "Not only have I fixed your ACL, but hopefully I've changed your geometry so you don't re-tear it," Levitz said. And once the notchplasty is completed, in about 10 minutes, "you should be able to see exactly where that ACL belongs on the femur side."
STEP FIVE: THE TUNNELS
The natural ACL inserts on the back wall of the femoral bone. "We can't get it to stick there, so we have to stick it in the bone," Levitz said. "You're basically trying to drill a perfect hole, one that has about two millimeters of bone on the outside. If you go too deep you blow out the back wall [of the bone]. If you go too far the other way the ACL is more susceptible to re-tearing. If you want to do it perfectly you have to be a millimeter from disaster." A tunnel is first drilled through the top of the tibia bone where those fragments of the original ACL were left behind. The tunnel is 10 millimeters wide and is drilled with an acorn reamer that works similarly to the way tunnels are dug under rivers or through cities. Like putting in golf, most of the time on this portion is spent lining it up. The actual drilling takes about a minute. The femoral tunnel is more difficult and fraught with dangers. Traditionally the knee is flexed and the same reamer is used to go through the tibia and then through the femur. Levitz was taught by Andrews to do it freehand, though, to prevent the new ACL from becoming too vertical and recreating a more natural anatomical position. "He was able to learn and teach his fellows how to feel the drill rub against the back wall [of the femur] so you can glide with your hand along that millimeter and keep it right there," Levitz said of Andrews. "It's a feel thing. That's arguably why his athletes have so much success." The actual drilling of the femoral tunnel takes another minute.
STEP SIX: THE INSERT
Now there are two tunnels above and below the knee joint that need to be connected with the patella tendon. A pin goes through the tunnel in the tibia, through the femoral tunnel, and out through the skin at the top of the knee. Attached to the pin are two threads, and those are attached to the top of the graft. The graft is fed through the tibial tunnel, through the knee -- "often you need a little movement, a little wiggle, to get it in there," Levitz said -- and the femoral plug goes into the socket and locks in with a compression fit. "You almost have to knock it in so that it's not going anywhere," Levitz said. The ligament is then attached to the femoral side most often with an interference screw made of bioabsorbable plastic or calcium phosphate that does not necessarily secure the bone and tendon but "smushes everything together" and adds to the compression fit. "We're creating interference so the graft won't slide out." Now the surgeon pulls on the tendon from below as hard as he can to make sure it is not going anywhere. The tendon is then tensioned to the proper tautness with the knee flexed at about 30 degrees. The tibial side is secured with an interference screw as well. "At that point, the case is pretty much done," Levitz said. "If everything looks good we'll pull the sutures out, close the graft wound and go home."